The present invention relates to a novel gravure ink binder for paper, and more particularly to the binder being capable of providing gravure inks excellent in drying property and gloss, and also to a process for preparing the same.
Gravure inks for paper are generally manufactured by blending pigments with a varnish prepared by dissolving rosin or a modified rosin as a binder in an organic solvent. In order to improve the drying property, gloss and other properties, it has been tried to modify the rosin, or to partially or completely replace the rosin binder with another binder such as a petroleum resin. For instance, it is proposed in U.S. Pat. No. 3,468,829 to use metal salts of petroleum resin modified with an .alpha.,.beta.-dicarboxylic acid, esterification products thereof, or mixtures of the salt and rosin salt and/or modified rosin salt. However, inks empolying such binders are not necessarily satisfactory in drying property, gloss and odor. It is also proposed in Japanese Public Disclosure No. 42093/1973 to use a binder prepared by reacting a cyclopentadiene polymer with an unsaturated fatty acid, and if desired, further with an acrylic acid and/or acrylic ester monomer, in the presence of a metal compound. Such a binder is also unsatisfactory in the drying property and odor of inks and the gloss of printed face.